Question For Stock Tank/ Alli Snapper Owners

My turtle is now constantly trying to get out of his stock tank from midnight through noon. I have a wood frame with lattice and pad locks. I also lay some heavy, long 4x4x8's across it to keep him from lifting the lid. This morning he was using a great deal of force to lift the entire lid up. His water is clean, he is well fed (1 chick or several large crawfish every day or so in addition to whatever 5" fish he catched). I'm wondering what I can do to make him happy in his artificial home. Do your adult alligator snappers try to get out?